Storytime:
I see at least one wedding per week (it'll be two just today! Working in a related industry will do that...) and the absolute majority of those has at least one partner in complete stress-induced meltdown-mode at least until the main part is done, everyone's been fed and watered and all that's left to do is to party.
These are healthy (and sometimes very, very sheltered) people and they can't handle the stress of a wedding all that well.
Add that acronym of ours and its lovely ways of messing with thoughts and emotions to the mix and it'll get that much harder.
BUT! I'd say you're doing well! You made it this close to the date without running for the hills, which is more than some can claim for themselves (*cough**blush*) - you can go all the way now.
Is there anything you like to do to unwind? I know the last days before a wedding don't really have enough hours in the day already, but some things are just so important that one should be making the time, even if it's just to go for a long walk or whatever may help you catch your breath.
You'll be fine, it'll be a beautiful day and you'll BOTH be happy you took the plunge. Just keep on taking care of yourself until the day comes. :)
And now one more thing that I hope you don't misunderstand:
Whether you deserve him or not...is not for you to decide. That is his call, and he obviously made it.
No matter how you may be feeling about yourself right now, he wants to spend the rest of his life with you and I'd say that's a pretty clear sign that you do deserve him. He loves you for everything you are and he wants that whole package in his life every day.
He knows you deserve him even if you can't believe it right now. If there's any way at all you might be able to let that thought carry you through this nutso-stressful pre-wedding days, please try not to fight it.
There's absolutely nothing "wrong with you", especially not in his eyes. Take care of yourself, keep on keeping on, and I wish you both a beautiful wedding day and a wonderful marriage. :)